With the continuous development of liquid crystal display (LCD) technology, the requirement on the resolution of display devices is becoming higher and higher. Currently, full high definition displays have become the mainstream. FIG. 1 is a schematic structural view of an array substrate of a high-definition (HD) display device. In order to obtain a full high definition display device, as illustrated in FIG. 1, an organic resin layer 8 need be formed on source electrodes 6 and drain electrodes 7 of thin-film transistors (TFTs) to reduce the power consumption of the array substrate and increase the aperture ratio. Meanwhile, a through hole need be formed to connect the drain electrode and a pixel electrode layer 14. Finally, a voltage difference is produced across a common electrode layer 12 and the pixel electrode layer 14. Therefore, the normal display of the sub-pixel function can be guaranteed.